Fluid pump with a continuously variable speed converter

Abstract

A continuously variable speed converter is incorporated in a main housing of a fluid pump and is drivingly connected at an output shaft thereof to a pump rotor so as to transmit the driving power of an engine to the pump rotor at various output/input speed ratios. An actuator is operatively connected at its piston to a speed change mechanism of the speed converter and is responsive to pressurized fluids, which are delivered from the pump, respectively, through and not through a throttle element provided on an outlet passage of the pump. The piston is biased by means of a spring to operate the speed change mechanism to maintain constant the pressure difference between fluids before and behind the throttle element, so that fluid may be delivered from the pump approximately at a predetermined flow rate regardless of changes in engine rotational speed.

What is claimed as new and desired to be secured by Letters Patent of the United States is: 
     
       1. A fluid pump driven by an engine, comprising: a main housing having an outlet passage;   a continuously variable speed converter provided in said main housing and composed of input and output shafts rotatably carried by said main housing in axial alignment with each other and of a pair of friction discs provided respectively on said input and output shafts in face-to-face relation for frictionally transmitting rotational driving power to said engine from said input shaft to said output shaft at various output/input speed ratios;   a pump casing received within a pressure chamber formed in said main housing and having an internal cam bore;   a pump rotor mounted on said output shaft for rotation together therewith and received in said internal cam bore;   side plates urged to be held in contact with both side surfaces of said pump casing and said pump rotor disposed therebetween for enabling said pump casing and said pump rotor to deliver pressurized fluid into said pressure chamber and said outlet passage when said pump rotor is rotated, said pump casing, said pump rotor and said side plates being integrally movable in an axial direction of said output shaft so as to press one of said friction discs toward the other friction disc when pressurized fluid is supplied into said pressure chamber;   a throttle element provided in said outlet passage;   an actuator having a movable member whose two separate fluid reactive surfaces are responsive respectively to pressurized fluids which are delivered by the rotation of said pump rotor respectively through and not through said throttle element;   a speed change mechanism incorporated in said speed converter for changing the transmission ratio of said rotational driving power from said engine to said pump rotor and being operatively connected with said movable member so as to be controllably operated thereby; and   means cooperating with said actuator for operating said speed change mechanism to maintain approximately constant the pressure difference between fluids before and behind said throttle element.   
     
     
       2. A fluid pump as claimed in claim 1, wherein said means cooperating with said actuator comprises a spring for urging said movable member to move in one direction. 
     
     
       3. A fluid pump as claimed in claim 1, wherein said speed converter is further composed of a plurality of balls provided between said pair of said friction discs in contact therewith for transmitting driving power therebetween, and wherein said speed change mechanism is arranged to tilt the rotational axis of each of said balls when operated by said movable member. 
     
     
       4. A fluid pump as claimed in claim 3, wherein said speed change mechanism comprises: a retaining member fixedly provided between said pair of said friction discs;   a plurality of pivot shafts carried on said retaining member for pivotal movement in respective planes, each including the axis of said input shaft;   a plurality of rollers respectively rotatably carried on said plurality of said pivot shafts and cooperating with one another to hold said plurality of said balls in contact with said pair of said friction discs; and   a member engaged with said plurality of said rollers and connected to said movable member so as to pivot said plurality of said pivot shafts when moved by said movable member.   
     
     
       5. A fluid pump as claimed in claim 4, further comprising: a plurality of radially movable vanes retained by said pump rotor and urged to contact with an internal cam surface formed on said pump casing.